overoptimistic

overoptimistic /ˌoʊvɚˌɑːptəˈmɪstɪk/ adjective
overoptimistic
/ˌoʊvɚˌɑːptəˈmɪstɪk/
adjective
Britannica Dictionary definition of OVEROPTIMISTIC
disapproving
: expecting something to be much better in the future : too optimistic